From an engineering standpoint, the Burj Khalifa represents a triumph over gravity, wind, and material limits. Its buttressed core system — a hexagonal central core buttressed by three wings — allows the tower to resist the tremendous lateral forces of wind at 800+ meters. The concrete mix was specially formulated to withstand the extreme pressures at the base (over 200 MPa) while remaining pumpable to record heights. The cladding system had to accommodate thermal expansion of up to 1.5 meters over the building's height. Every system pushes the boundaries of what materials and physics allow.